1. Field of the Invention
The invention relates to an automatic fluid coupler, and more particularly, to a passive coupler mechanism for automatically connecting and disconnecting a fluid coupling between a movable pallet and a pallet support in response only to relative motion between the pallet and pallet support.
2. Description of the Related Art
In many manufacturing environments, one or more parts to be processed are loaded onto a movable pallet or fixture on a pallet at a load station. It is common for the parts to be secured to the fixtures or the pallet by means of clamping mechanisms which utilize pneumatic or hydraulic actuators such as a piston and cylinder. Therefore, it is necessary that the pallet have access to a source of fluid power. Typically, the fluid source is remote from the pallet and is supplied to the pallet by hoses terminating with quick disconnect couplings which are automatically or manually connected to the pallet at the load station. After the parts are loaded on the pallet, pressurized hydraulic fluid is applied from the fluid source to operate clamps thereby locking the parts in position. The pressure is maintained by blocking valves, and the fluid supply is disconnected from the pallet. Thereafter, the pallet is moved to a machining station, and the clamps under the fluid pressure hold the parts in position during machining. When the machining process is completed, the pallet is moved back to the load station, the source of fluid is connected to the pallet; and clamps are depressurized, thereby permitting the finished parts to be unloaded.
The load and machining stations may both be located at the machine, and the pallet is simply shuttled therebetween. Alternatively, two pallets may be used, and pans are unloaded and loaded from one pallet located at the load station while the second pallet is located at the machining station. The pallets are then rotated between the machining and load stations. In other environments, the pallet may be loaded and unloaded at a part load station remote from the machine; and the pallet is then transported from the remote load station to a station at the machine.
In order to couple the fluid source to the pallet, a pair of fluid coupling members, typically male members, are located on a side surface of the pallet. A pair of mating female fluid coupling members are connected via hosing to the fluid pressure and return lines of a fluid source. After the pallet is located at the load station, the couplings may be manually connected and disconnected. If a powered automatic coupler is used, a powered slide containing a first pair of coupling members is located adjacent the side of the pallet containing the mating the pair of coupling members. A logic controller associated with the coupler executes a couple and unclamp cycle which automatically moves the slide with the first coupling members to an engagement position with respect to the mating coupling members mounted on the pallet. When in the engaged position, the fluid couplings are made, or connected, and the clamps may be manually or automatically released.
With some designs, the automatic coupler secures the couplings by physically holding the coupling members together. With other designs, the automatic coupler uses self-locking, quick disconnect couplings; and an actuator operates sliding collars on the pair of female couplings which is mounted on the powered slide. By controlling the operation of the actuator in conjunction with motion of the powered slide, the couplings are disconnected; and the powered slide is moved back to its original position away from the pallet.
With the clamps released, the operator may move the pallet to various positions to unload and load workpieces therefrom. After all the workpieces have been exchanged, the pallet is oriented to position the side with the pair of male coupling members adjacent the powered automatic coupler. The powered slide moves the pair of female coupling members to the engagement position thereby connecting the fluid path. The clamps are automatically or manually engaged, the couplings are released and powered slide is retracted from the pallet. The above described system has a disadvantage of requiring very accurate positioning of the automatic coupler relative to the pallet because the coupling members have limited compliance to compensate for a positioning misalignment therebetween. Using the coupling members as an aligning mechanism produces excessive wear on the coupling faces and may also result in the coupling unit binding as the coupling members attempt to force themselves into alignment. The above automatic system has a further disadvantage in that the coupling members mounted on the side of the pallet are exposed to chips and contamination from the machining environment.